Activated sludge installation with concentrically arranged circular tanks with one circular tank an aerating tank and rapidly running bridge



United States Ratent lnwntors .lurgen Seipp:

August Schreiber. Hannover-Yinnhorst. Germ-am- Appl. No. 698.236 Filed Jan. 16.1968 Patented Oct. 13. 1970 Assignee August Schreiber and Martin Danjes Priority Oct. 2. 1967.

Germany, Sch 41.377

ACTIVATED SLUDGE INSTALLATION WITH CONCENTRICALLY ARRANGED CIRCULAR TANKS WITH ONE CIRCULAR TANK AN AERATING TANK AND RAPIDLY RUNNING BRIDGE 8 Claims, 10 Drawing Figs.

U.S.Cl 210/195,

Int.Cl ..B01d2l/18; COZCl/34 FieldofSearch 210/195.

[56] References Cited UNITED STATES PATENTS 2.568.452 9/1951 Kellyetal 210:22lX 2.647.870 8/1953 Kelly etal.... 210/221 3.220.706 11/1965 Valdespino 210/195X 3.312.346 4/1967 Walker 210/195 3.353.677 11/1967 Thayeret a1... 210/256X 3.397.789 8/1968 Valdespino..... 2l0/221X 3.415.379 12/1968 Thayer .1 210/195 OTHER REFERENCES Smith and Loveless. "Oxigest-- Sewage Treatment Plant. Bulletin 1220-13. 1964.

Primary ExaminerJ. L. DeCesare AImrneyWatson. Cole Grindle and Watson ABSTRACT: An activated sludge installation having a centrally arranged circular tank with an aeration tank surrounding the centrally arranged tank and a centrally supported revolving bridge with compressed air and electric current supply means thereon and sludge scrapers for the centrally arranged circular tank.

l 1 l l l 4 t l l l Patented Oct 13, 1970 3,533,508

Sheet 1 of4 ika ywfl ill/Aw Patented Oct. 13; i970 Sheet F/GJ Judi,

Patented Oct. 13, 1970 Sheet IYIINIVENTORS A. Jclr'eqbar BY e? n Q' L D a ACTIVATED SLUDGE INSTALLATION WITH CONCENTRICALLY ARRANGED CIRCULAR TANKS WITH ONE CIRCULAR TANK AN AERATIN'G TANK AND RAPIDLY RUNNING BRIDGE This invention relates to an aeration tank for the treatment of activated sludge.

It has been known to provide an annular-shaped aeration tank around a centered, final sedimentation tank for the purification of activated sludge or a centered final sedimentation tank for mechanical purification. It has further been proposed to arrange above such installations, a revolving bridge, which is placed into revolving movement solely either by aeration or else is driven by a motor. The higher the revolving relative speed is selected between the activated sludge-water mixture and the aeration installations, the more favorable will be the utilization of the oxygen. At the same time, it will be irrelevant whether the aeration is accomplished from the direction of the bridge only or whether the aeration is accomplished from the direction of the bridge only or whether a fioor aeration has also been provided.

The present invention has for an object, in the case of activated sludge installations of the above mentioned type. to develop or to arrange the built-in aeration and energy supply installations, as well as the devices for the treatment of sludge, in such a manner that a perfect control or repair of the above mentioned installations will be possible beside a trouble-free operation and the greatest possible utilization of the oxygen.

For this purpose, the invention proposes that in the area of the center of the installation, devices for supply of compressed air and electric currents be provided for the revolving bridge which revolves rapidly and mounted centrally, to which removable aeration installations for the aeration tank and, furthermore, installations for the recirculation of activated sludge and sludge scrapers for the centered round basin or tank, if the latter serves as a final sedimentation tank, and only sludge scrapers, whenever the center circular tank serves as a presedimentation tank. Aeration devices are provided for a possible, additional fixed floor aeration. which can be placed up along the outside wall of the activating tank and arranged so that they can be pulled out from the aeration tank.

By the above mentioned characteristics, an operation free of disturbances as well as a good possibility for control or repair will be guaranteed. In detail, one will achieve by this invention that the quickly revolving bridge will be supplied simultaneously with compressed air for the aeration and also with current for the supply of the driving motor of the bridge. The invention, furthermore, is concerned with a special type of removable aeration devices attached to the bridge, sludge scrapers for the centered final sedimentation tank which likewise are either fixedly attached to the bridge and which move as rapidly as the rotation or which are connected with said revolving bridge by a transmission clutch and which move essentially more slowly than the revolving bridge. By simple devices through which, in the case of an additional fixed floor aeration, these aeration installations can be taken out or inserted quickly for the purpose of carrying out repairs or examination.

Further characteristics of the invention will be apparent from the following description when considered in connection with the accompanying drawings by way of example in which:

FIG. 1 is a vertical section showing an activated sludge installation with a centered round tank serving as a final sedimentation tank, for a small quantity of water with a small diameter;

FIG. 2 is a plan view ofthe installation ofFlG. 1;

FIG. 3 is a vertical section of a modified installation for larger quantities of water;

FIG. 4 is a plan view of the installation of FIG. 3;

FIG. 5 is a vertical section ofa removal aeration installation attached to a revolving bridge;

FIG. 6 is a top plan view of the aeration installation of FIG.

FIG. 7 is a vertical section of a centered final sedimentation tank showing a sludge scraper and a revolving bridge;

FIG. 8 is a partial top view of the sludge scraper of FIG. 7; FIG. 9 is a sectional view showing fixed floor aeration; and FIG. 10 is a top plan view of the structure of FIG. 9.

In the FIGS. I to 10, the following reference numbers are defined:

The concrete floor I centers the preor final sedimentation tank 15 and for the aeration tank 12 with the encompassing wall 2 of the centered prcor final sedimentation tank a feed device 3 provides compressed air and electric current to the rapidly revolving bridge 4, and removable aeration devices 5 and attached to the revolving bridge 4. The activated sludge return devices 6 cooperate with a final sedimentation tank 15 and the aeration tank 12, a sludge scraper 7 is mounted in the centered round tank 15 and the fixed floor aeration 8 is pro vided. The devices 9 are for taking out the floor aeration and the intake 10 is shown in FIGS. 2 and 4. The outlet 11 is connected to the aeration tank 12, and the intake 13 is connected from the activating tank 12 to the final sedimentation tank 15. The intake 14 has a settling chute or shaft for the final sedimcntation tank and the centered round tank 15 is the final sedimentation tank. Outlet trough 16 in the final sedimentation tank has sludge sliding surfaces 17 also in the final sedimentation tank. Sludge removal troughs 18 are provided in the final sedimentation tank 15 and a sludge collecting chute or sludge pump station 19 is provided adjacent the aeration tank 12. A driving motor 20 operates the revolving bridge.

The individual parts of the installations 3 to 9 have been provided subsequently with an additional numeral l9. According thereto, the reference numbers 61 to 69 were selected for individual parts of the device 6 for the return of the sludge.

The installations shown in FIGS. 1 and 2 by way of example is described as follows:

The sewerage, roughly purified by a screen flows by means of the intake 10 into the aeration tank 12. Here it is aerated by an aeration device 5 attached to the revolving bridge 4 and the developing sludge is always held in suspense. The revolving bridge 4 can be moved either by a damming shield which is kept in movement in cooperation with the ascending activated sludge and water-air mixture or by guide surfaces above the aerators, but it can also be kept in motion by an additional driving motor which is supported by the encompassing wall 21 of the aeration tank 12. The mixture of water and activated sludge then enters the intake and settling chute 14 by the connecting pipe 13, and the settling chute has been provided in the center of the final sedimentation tank 15. The mixture of water and activated sludge slowly flows downwards, precipitates at the same time and enters the final sedimentation tank 15 at the bottom. Here it is forced to rise slowly to the outlet trough 16, whereby the sludge that has been carried along sinks to the bottom, collects in the sludge collecting trough 18 of the final sedimentation tank 15 and is moved back again into the aeration tank 12 through the sludge return installation 6. The outlet trough 16 has an outlet pipe 11 at a distant point which allows the sewerage purified in this manner to run off to the main canal.

The aeration of the mixture of water and activated sludge is accomplished by means of the air distributors 51 of the aeration installation 5, whereby the air bubbles placed therein will rise in the mixture of water and activated sludge and are turned aside into the opposite direction of rotation of the revolving bridge 4 by one or several guide metal sheets or damming walls, so that the bridge 4 by the deflection of the rising mixture of water and activated sludge is moved in the direction shown by the arrow, FIG. 2. If the revolving bridge 4 is supported above the aeration or activated sludge tank 12 by a floating body, then the mixture of water and activated sludge will remain quiescent except for a narrower area of the installation 5. If the revolving bridge 4 is braked down in its rotation on the outside walls, then a slight revolving movement of the mixture of water and activated sludge will start in the aeration tank 12 in an opposite direction to the movement of the revolving bridge 4. If the bridge 4 is driven, then the contents of the tank are moved through the aeration device 5 and the rising air bubbles into a slight revolution in the rotational sense of the revolving bridge. By the baffle plates provided and by the revolving movement, a relative horizontal movement between the mixture of water and activated sludge and the rising air, is accomplished, and in that way a better utilization of the oxygen of the air supplied is accomplished.

The activating installations according to the design presented by way of example in FIGS. 3 and 4 operate in such a way, that crude waste water, which had been prepurified through a trash rake or screen or desludging installation. will flow by means of the intake into the aeration tank 12. There it will be aerated through the aeration devices 5 at tached to the revolving bridge 4 and through the stationary floor aeration installations 8 and will then reach the intake and settlement chute 14 by the connecting pipe 13; and then it is again deflected downwards whereby it flocculates and flows from the lower part of the settling chute into the center round tank 15 serving as a final sedimentation tank. Here the activated sludge that has been carried along sinks to the floor of the tank because of the low speed and is moved to the middle of the tank 15 by a sludge scraper 7 and from there it is returned to the aeration tank 12 by means of the sludge return installation 6. The sewerage purified in this manner flows by means of the outlet trough 16 of the final sedimentation tank 15 and through the outlet pipe I! to the main canal. In the case of the installation according to FIGS. 3 and d, the sludge scraper '7 of the centered round tank 15 is not rigid but it is coupled by a transmission of the revolving bridge 4, in such a manner that the sludge scraper 7 will revolve only about onetwentieth as fast as the revolving bridge 4.

The purification action at the same time takes place in such a manner that the aeration installation 5 attached to the revolving bridge 4 is driven, as a result of which a movement of the mixture is brought about in the aeration tank 12 by the resistance of the parts of the aeration installation 5 located in the mixture of water and activated sludge and through the air bubbles rising in the direction oftravel of the revolving bridge. Since, however, air is blown in also through the stationary aeration installations 8, these rising air bubbles constitute a resistance for the mixture of water and activated sludge dislodged by the bridge 4 and the aeration installation 5. For that reason the mixture of water and activated sludge must flow above the stationary floor aeration installations 8 transversely in the direction of the revolving movement of the bridge 4, while the mixture ofwater and activated sludge must flow through above the movable aeration installations 5 transversely in the opposite direction of the movement of the revolving bridge. The faster the revolving bridge 4 is moved, the stronger becomes the horizontal flow through the rising air bubbles and the more favorable will be the utilization of oxygen, until it reaches a state where the increased driving energy with the improved utilization of oxygen of the air placed therein will no longer offer any advantage. In this manner and at the same time a good and even better utilization of oxygen will be achieved than in the case of aeration according to the activating installations according to FIGS. 1 and 2.

The installations 3 for supply of air and current leading to the revolving bridge 4 consist, in the case of the installations according to FIGS. 1 and 2, of an air supply pipe 31 which leads upward from the floor 1 or below said floor to the center of the installation and from there with a right-angled branch and with an ascending tube 32 connected just above the floor 1. The vertical ascending tube 32 reaches so far into the revolving bridge 4. In the latter, seals and bearings have been provided which guide the air in a hollow supporting beam 33 of the revolving bridge 4. The prolongation of the stationary tube 32 reaches through the revolving bridge 4 and there it has stationary slip rings 34, on which sliding contacts revolve which are moved together with the bridge. The electric current reaches the sliding contacts that are firmly connected with the revolving bridge 4 by a supply cable which is guided into the air supply tube 3! and 32 beyond the rotatable air branch to the revolving bridge, up to the stationary slip rings. The electric current is conducted from these sliding contacts to the driving motor of the revolving bridge.

According to the designs following FIGS. 1 and 2 given by way of example, the central mounting on the air supply pipe 32 has been made rotatable with the movable part of the support, which is firmly connected with the revolving bridge 4, a casing pipe 35 can also be connected solidly and airtight, so that the air seal is made, not against atmospheric pressure, but against an increased pressure which develops by the pressure of the mixture of activated sludge and water within the final sedimentation tank l5 up to the lower end of the casing pipe 35.

The air and current supply in the case of the activating in stallations according to FIGS. 3 and 4 have also been conducted to the middle of the tank 15 through the air supply pipe 31. From here too, the air is conducted, again in an ascending tube 32, up to below the revolving bridge 4 and by means of an elastic connection to the sealing rings in the air supply pipe 33. provided in the revolving bridge, which pipes can also be made as hollow supporting beams for the revolving bridge 4.

The support of the revolving bridge 4, in the case of these designs given by way of example, is accomplished not on the central air supply pipe 32, but on the encompassing wall of the intake and settling chute or tube 14 of the final sedimentation tank 15. The electric current is also conducted through a cable leading in the air supply pipe 32 up to the sliding contacts of the revolving bridge 4.

The aeration installations 5, which are removable and which are attached to the revolving bridge 4, according to FIGS. 5 and 6, consist of air distribution pipes 51, which are attached to a preferably square air supply pipe 52. The latter is again conducted downwards on top by means of an degree elbow up to a releasable coupling 53 and is conducted in the connecting sleeve 54 which leads up to the air distributing pipe 33 of the revolving bridge 4. The air supply pipe 52 is guided in a guide rail 56, which is open toward the air distributors 51, up to a tilting connection 55 developed as a hinge, and then enters a pipe guide 57 which is closed on all sides and which is connected with the lower pipe guide 56 only by the hinge.

On the upper side of the closed pipe guide 57, a removable winch 58 has been attached on the outside, which reaches the lower part of the air distributor 51 with its traction rope 59.

If the aeration installations are to be lifted out of the water, then the releasable coupling 53 is opened and is pulled up by the winch 58, which is firmly connected with the lower guide and the revolving bridge 4 by the hinge 55, until the suspension device of the rope 59 will be on the air distributors 51 below the closed pipe guide 57. Then the air distributors 51 are turned with the pipe 52 and the closed guide 57 by the hinge 55, so that the air supply pipe 52 inclusive of the closed guide 57 come to lie in a horizontal position with the winch 58 by the bridge 4. The air distributing pipe 51 will then be directly beside the revolving bridge 4 and can be examined and exchanged from its foot bridge.

For the purpose of insertion into the mixture of activated sludge and water, the entire device 51, 52, 57 and 58 is again turned into a perpendicular position and is again lowered by' the winch.

The guide rail 56, which is open toward the side of the air distributor pipes 51, has at its lower end, a plate with a lock opening 60, with which a mandrel of the air supply pipe 52 fits, as a result of which the aeration installation, after closing the releasable coupling 53 again, will be firmly connected with the revolving bridge and will be operable again.

According to the design, following FIGS. 1 and 2 by way of example, the sludge scraper 7 has been firmly coupled with the rapidly revolving bridge 4 by means of the sludge return pipe 35. It has a bearing arm 71, to which a chain 72 has been attached, which slides on the inclined sliding surface and thus moves the sludge in the direction of the sludge trough 18 of the final sedimentation tank. The sludge scraper 7 then moves as fast as the revolving bridge 4. The bearer arm 71 for the sludge chain 72 and the latter itself have been developed in their cross sections favorably so as to present resistance, so that the contents of the final sedimentation tank 15 will not be put into a harmful revolving movement.

In the case of the design according to FIGS. 3 and 4, the sludge scraper 7 has been coupled with the revolving bridge 4 by a revolving gear. On its lower side the scraper is firmly connected with the gear rim 76, FIGS. 7 and 8, and it has been mounted on the outside by a roller on the separating wall 2 of the final sedimentation tank 15.

The gear 74, which meshes with the gear rim 73. is connected rigidly with the gear 75 and the latter again meshes with the gear rim 76. The gear rim 73 has been firmly mounted on the encompassing wall 14 of the intake and settling chute, and it stands still. The supports of the gear 74 and 75 are firmly connected with the revolving bridge. The gear rim 73 has fewer teeth than the gear rim 76, as a result of which the sludge scraper 7 will be moved more slowly by a certain ratio in the case ofa revolution of the revolving bridge 4. The ratio must be such that a stirring up of the settled sludge in the final sedimentation tank will be avoided. Naturally it will also be possible to use instead of this gear connection some other designs, for example, bevel gears with varying tooth distributions on the revolving bridge 4 and aligned toward the center axis of the revolution. In a manner already known, the sludge scraper 7, located on the floor, will then be attached to the revolving arm 77, which moves the sludge from the floor of the final sedimentation tank toward the middle, from which said sludge is moved by the sludge return device 6 back again into the aeration tank 12.

If in the case ofa sewage treatment plant the sewage is to be prepurified mechanically prior to entry into the aeration tank 12, then the crude sewage is fed to the central round tank and, after a certain tarrying time and removal of sludge, it is fed to the aeration tank 12. The sludge which settles from the crude sewage is then naturally not moved to the aeration tank 12 but to a sludge treatment installation. The mixture of activated sludge and water from the aeration tank 12, in this case, is guided into a separate final sedimentation tank, and the settled activated sludge of this final sedimentation tank is carried back again into the aeration tank 12.

The aeration installations 8 for the fixed floor aeration, according to designs following FIGS. 3 and 4, are lifted from the mixture of sludge and water similarly as the aeration for the rapidly revolving bridge 4 and are then swung out from the aeration tank 12 beside the installation. This aeration device 8 consists, according to FIGS. 9 and 10, again of the air distributor pipes 31, which together with a main supply pipe 82 lead upwards and are connected there with an airtight and releasable coupling 83 by a pipe elbow 84 with an air supply pipe 85 located outside the installation. The main supply pipe $2 is guided in a guide rail 86 and at its lower end it has been provided with a hook on which a wire cable has been provided for lifting out the aeration installation. Above the encompassing wall 2 of the central circular tank 15, two guide rails 90 and 91, FIG. 9, have been attached, through which the main pipe of the air distributor pipe 81 is additionally guided.

Outside the encompassing wall 21, a casing 88 has been provided in which a lifting device 89 with'the guide rails 90 and 91 for the main supply pipe 82, which is to be pulled up, and a winch 92 has been provided. This lifting device 89 is swingably mounted in the casing 88. After lifting the air distributor pipes 81 with the air supply pipe 82, everything is pulled up above the edge of the outside wall 21 and then the entire section of the floor aeration is swung outward from the area above the aeration tank 12 by the lifting device 89.

If the air distributor pipes have been examined or replaced and are again to be inserted therein, then they are again swung by the lifting device 89 across the outside wall into the area of the aeration tank 12, are inserted onto the guide rails 86 and are lowered to the floor of the tank. Then the movable elbow 84 is again firmly connected with the main supply pipe 82 by means of the coupling 83 and the air supply operates again normally.

We claim:

1. Activated sludge installation comprising a centrally-arranged circular tank, an aeration tank including aerators surrounding the centrally-arranged tank, a centrally-supported revolving bridge, compressed air and electric current supply installations arranged within the area of the middle of the centrally-arranged tank and serving to supply compressed air and electric current to the centrally-supported revolving bridge, activated sludge return installations together with sludge scrapers for the centrally-arranged circular tank, means to feed influent to the aeration tank, means to remove effluent from the centrally-arranged tank, means to recirculate sludge from the centrally-arranged tank to the aeration tank, means to rotate the bridge, means to connect the aerators to the bridge for rotary movement, and means to lift and swing the aerators together with their connecting means out of the tank,

2. Activated sludge installation according to claim 1, in which a perpendicularly fixed compressed air branch is pro' vided in the floor of the circular tank and extends from the outside to the middle of the circular tank, up to a bearing of the revolving bridge, said branch being connected to a hollow girder supporting and forming the revolving bridge, and said girder being provided with outlets from which compressed air can be taken for the aerators attached to the revolving bridge or for the activated sludge return installations.

3. Activated sludge installation according to claim 2, in which the bearing of the revolving bridge is an airtight revolving connection and in which a casing pipe is provided sealed with a rotating part of the airtight revolving connection and extending downwardly into the area of a sludge trough of the centrally-arranged tank.

4. Activated sludge installation according to claim 1 in which a guide strip is provided rigidly attached to the revolving bridge and extends downwards to near the bottom of the aeration tank and is opened in the direction of the aerators, said strip having at its lower end an insertion opening and at its upper end a tilting connection for an air supply pipe of the aerators which pipe can be pulled up along the guide strip and tilted for purposes of control and replacement of the aerators, and a winch connected to the guide strip.

5. Activated sludge installation according to claim 2, in which the centrally-arranged circular tank is provided as the final sedimentation tank, and in which a sludge return pipe is provided firmly connected with the revolving bridge, said sludge return pipe being arranged parallel to and outside of the perpendicularly fixed compressed air branch and extending downwards into the area of a sludge trough of the centrally-arranged tank and being provided with a compressed air supply line coming from the revolving bridge, said sludge return pipe in its upper area extending below the revolving bridge and emerging above the aeration tank so that, when compressed air is added, settled activated sludge is moved from the bottom part of the final sedimentation tank by pump action to the aeration tank.

6. Activated sludge installation according to claim 1, in which a sludge return pipe is provided bent radially outwardly in its lower area and terminates in a concentric sludge collecting trough provided in the circular tank.

7. Activated sludge installation according to claim 1, in which the sludge scrapers for the central circular tank are coupled firmly with the revolving bridge by a rotatable bearing provided with a gear transmission driven so that it will revolve with a sufficiently low speed.

8. Activated sludge installation according to claim 1, in which bottom aerators are provided for floor aeration, said bottom aerators consisting of a guide rail attached on the inside of the outer wall of the aeration tank and opened in the direction opposite to said outer wall, and in which the bottom aerators furthermore consist of an air supply pipe leading to the aerators arranged at its lower end, whereas at-the upper end of the air supply pipe a releasable connection with a main compressed air supply pipe guided toward the inside is arranged, and in which the bottom aerators furthermore consist of a lifting and swinging device arranged separately by which the bottom aerators can be pulled up along the ,outside wall of the aeration tank and swung out of the aeration tank for the purpose of examination or repair. 

